Liquid-Phase Co-Exfoliated Graphene/MoS2 Nanocomposite for Methanol Gas Sensing.

We developed an efficient method to co-exfoliate graphite and MoS2 to fabricate graphene/MoS2 nanocomposite. The size, morphology, and crystal structure of the graphene/MoS2 nanocomposite were carefully examined. The as-prepared graphene/MoS2 nanocomposite was fabricated into thin film sensor by a facile drop casting method and tested with methanol gas in various concentrations. The sensitivity, response time, and repeatability of the graphene/MoS2 nanocomposite sensor towards methanol gas were systematically investigated. A pure MoS2 based thin film sensor was also prepared and compared with the nanocomposite sensor to better understand the synergetic effect in the sensing performance. Our research demonstrated that compositing MoS2 with graphene could overcome the shortcoming of MoS2 as a sensor material and bring in a promising gas-sensing performance with a quicker response/recovery time and an enhanced sensitivity. Moreover, this composited material with a distinct structure and an excellent electronic property is expected to have potential application in various fields, such as optoelectronic.

Efficient exfoliation of MoS2 with volatile solvents and their application for humidity sensor. .

Liquid-phase exfoliation is likely to be feasible for practical fabrication of few-layer MoS2 nanosheets in large quantities. However, this method generally involves the organic solvents with high boiling point; new strategy using low-boiling-point solvents to obtain high MoS2 concentration is still highly required. In this study, using the strategy of Hansen solubility parameters (HSP), a method based on exfoliation of MoS2 in chloroform/acetonitrile mixtures is demonstrated to fabricate high concentration MoS2 nanosheet solution. The highest concentration of few-layer MoS2 nanosheets and nanoparticles up to 0.4 mg/ml is achieved with the optimum composition of mixture. The MoS2 nanosheet thin film is also investigated in terms of their sensing properties towards humidity. The exfoliated MoS2 based thin film sensor exhibited excellent sensitivity, quick response and recovery, and good reproducibility comparing to their bulk counterpart. The excellent sensing performance of exfoliated MoS2 is generally attributed to the high surface-to-volume-ratio and increased ratio of edge sites and basal plane sites after exfoliation.